Aiyoh, this bisa jadi anemia la, especially kalau diet tak balanced atau period flow yang heavy, a few of my mum friends pernah complain pasal sudden dizziness macam tu. Best is to do a blood test dulu to check your HB level, then kalau confirmed low, doc boleh recommend iron supplements or dietary changes like more red meat, spinach, dates etc; jangan try guess-guess sendiri because bisa be other things jugak, so better settle it with a check-up ye